Audi will reveal a revised version of the A8 luxury saloon at the Frankfurt Motor Show in September, with subtle styling changes, new technology and more efficient engines.

It has new design headlamps and rear light elements, as well as a re-scuplted bonnet, while engines are more powerful while offering better efficiency.

There is a choice of seven petrol and diesel engines, the majority of which have been revised to improve performance and efficiency. The supercharged 3.0 TFSI petrol engine is boosted from 290hp to 310hp, the V8 twin-turbo 4.0 TFSI moves from 420hp to 435hp, the 3.0 TDI clean diesel increases from 250hp to 258hp and the 4.2 TDI clean diesel gains 35hp, taking it to 385hp. Its already mighty torque output is also increased by 37lb-ft to 627 lb-ft.

Paired with Quattro all-wheel drive, the 4.0 TFSI now powers the A8 from 0 to 62 mph in 4.5 seconds, but under partial load the Audi cylinder on demand (COD) system deactivates four of its eight cylinders to give priority to fuel economy.

The most efficient diesel engine is the 3.0 TDI, which returns up to 47.9 mpg, corresponding to 155/km of CO2 - 3g/km lower than the current version. All engines satisfy the Euro 6 standard, helped by friction-reducing measures which reduce fuel consumption by as much as 10%.

Improvements have also been made to the optional assistance systems. Audi active lane assist, which makes slight steering adjustments when necessary, is new to the A8, as is the park assist system with 360° display, which handles steering when parking, and the head-up display, which projects important data in the driver's field of vision on the windscreen. The night vision assistant can now also recognise larger animals in addition to pedestrians.

The revised Audi A8 is expected to reach its first UK customers in January 2014. Full pricing and UK specification information will be announced in due course.